Afferent and efferent projections of the mesopallium in the pigeon ( Columba livia )

142

This essay reviews step by step the conceptual changes of the updated tetrapartite pallium model from its tripartite and early tetrapartite antecedents. The crucial observations in mouse material are explained first in the context of assumptions, tentative interpretations, and literature data. Errors and the solutions offered to resolve them are made explicit. Next, attention is centered on the lateral pallium sector of the updated model, whose definition is novel in incorporating a claustro-insular complex distinct from both olfactory centers (ventral pallium) and the isocortex (dorsal pallium). The general validity of the model is postulated at least for tetrapods. Genoarchitectonic studies performed to check the presence of a claustro-insular field homolog in the avian brain are reviewed next. These studies have indeed revealed the existence of such a complex in the avian mesopallium (though stratified outside-in rather than inside-out as in mammals), and there are indications that the same pattern may be found in reptiles as well. Peculiar pallio-pallial tangential migratory phenomena are apparently shared as well between mice and chicks. The issue of whether the avian mesopallium has connections that are similar to the known connections of the mammalian claustro-insular complex is considered next. Accrued data are consistent with similar connections for the avian insula homolog, but they are judged to be insufficient to reach definitive conclusions about the avian claustrum. An aside discusses that conserved connections are not a necessary feature of field-homologous neural centers. Finally, the present scenario on the evolution of the pallium of sauropsids and mammals is briefly visited, as highlighted by the updated tetrapartite model and present results.

Section: Connectivity Of the Claustro-insular Lpall With Thoughts Onmentioning

confidence: 74%

Section: Connectivity Of the Claustro-insular Lpall With Thoughts Onmentioning

confidence: 99%

Comments on the Updated Tetrapartite Pallium Model in the Mouse and Chick, Featuring a Homologous Claustro-Insular Complex

Puelles

2017

142

“…These seasonal variations underlie behaviours like song learning, food caching and brood parasitism in songbirds, but these behaviours are absent in the ruffed grouse, so a lack of seasonal variation in TELE size was unsurprising. Similarly, the mesopallium is a multisensory, multimodal telencephalic region implicated in a wide range of behaviours [Timmermans et al, 2000;Reiner et al, 2005;Nakamori et al, 2010;Avey et al, 2011;Jeanne et al, 2011;Atoji and Wild, 2012;Shanahan et al, 2013]. As a result of its multifunctional nature, the mesopallium is unlikely to be directly tied to drumming behaviour, which is why we did not expect to find a seasonal difference in mesopallial volume.…”

Section: Discussionmentioning

confidence: 67%

“…The mesopallium is a multimodal, multisensory telencephalic region involved in higher processing and a wide range of behaviours [Timmermans et al, 2000;Reiner et al, 2005;Atoji and Wild, 2012;Shanahan et al, 2013]. Because of its multifunctional roles, the mesopallium as a whole is unlikely to be directly linked with drumming behaviour and also unlikely to vary in function between sexes or seasons.…”

Section: Cytoarchitectural Bordersmentioning

confidence: 99%

Seasonal Variation in Forebrain Region Sizes in Male Ruffed Grouse (Bonasa umbellus)

Krilow

Iwaniuk²

2015

The song system of songbirds has provided significant insight into the underlying mechanisms and behavioural consequences of seasonal neuroplasticity. The extent to which seasonal changes in brain region volumes occur in non-songbird species has, however, remained largely untested. Here, we tested whether brain region volumes varied with season in the ruffed grouse (Bonasa umbellus), a gallinaceous bird that produces a unique wing-beating display known as ‘drumming' as its primary form of courtship behaviour. Using unbiased stereology, we measured the sizes of the cerebellum, nucleus rotundus, telencephalon, mesopallium, hippocampal formation, striatopallidal complex and arcopallium across spring males, fall males and fall females. The majority of these brain regions did not vary significantly across these three groups. The two exceptions were the striatopallidal complex and arcopallium, both of which were significantly larger in spring males that are actively drumming. These seasonal changes in volume strongly implicate the striatopallidal complex and arcopallium as key structures in the production and/or modulation of the ruffed grouse drumming display and represent the first evidence of seasonal plasticity in the telencephalon underlying a non-vocal courtship behaviour. Our findings also suggest that seasonal plasticity in the striatopallidal complex and arcopallium might be a trait that is shared across many bird species and that both structures are related to the production of multiple forms of courtship and not just learned song.

“…However, the mesopallium, which lies just dorsal to the nidopallium, is even more enlarged in the New Caledonian crows [Mehlhorn et al, 2010]. The significance of this observation remains unclear, but the neural circuits that pass through the mesopallium are largely parallel to, and tightly interconnected with, the nidopallial circuits [Atoji and Wild, 2012]. It is likely, therefore, that meso-and nidopallium work closely together and are involved in similar functions.…”

Section: Neural Substrates Of Complex Cognition In Birdsmentioning

confidence: 89%

Bird Brains and Tool Use: Beyond Instrumental Conditioning

Striedter

2013

Few displays of complex cognition are as intriguing as nonhuman tool use. Long thought to be unique to humans, evidence for tool use and manufacture has now been gathered in chimpanzees, dolphins, and elephants. Outside of mammals, tool use is most common in birds, especially in corvids and parrots. The present paper reviews the evidence for avian tool use, both in the wild and in laboratory settings. It also places this behavioral evidence in the context of longstanding debates about the kinds of mental processes nonhumans can perform. Descartes argued that animals are unable to think because they are soulless machines, incapable of flexible behavior. Later, as human machines became more sophisticated and psychologists discovered classical and instrumental conditioning, skepticism about animal thinking decreased. However, behaviors that involve more than simple conditioning continued to elicit skepticism, especially among behaviorists. Nonetheless, as reviewed here, strong behavioral data now indicate that tool use in some birds cannot be explained as resulting entirely from instrumental conditioning. The neural substrates of tool use in birds remain unclear, but the available data point mainly to the caudolateral nidopallium, which shares both functional and structural features with the mammalian prefrontal cortex. As more data on the neural mechanisms of complex cognition in birds accrue, skepticism about those mental capacities should continue to wane.